Cairina moschata is a large duck native to Mexico, Central, and South America. They are a large duck, with the males measuring about 76 cm in length, and weighing up to 15 pounds. Females are considerably smaller and only grow to 7 pounds, roughly half the males' size. The bird is predominantly black and white, with the back feathers being iridescent and glossy in males, while the females are drabber. The amount of white on the neck and head is variable, as well as the bill, which can be yellow, pink, black, or any mixture of these. They may have white patches or bars on the wings, which become more noticeable during flight. Both sexes have pink or red wattles around the bill, those of the male being larger and more brightly coloured.Muscovy ducks have long claws on their feet and a wide flat tail. Male Muscovy ducks have spiralled penises which can become erect to 20 cm in one-third of a second. Females have cloacas that spiral in the opposite direction to try to limit forced copulation by males.